From my limited perspective, it doesn't sound like it's your decision to make. If you've made your opinions clear to the CEO, that's great and you've already fulfilled your duty. Let the co-founders sort it out between them, it may take time to transition the lackluster technical co-founder into a new role. If business is going well, it's unlikely he would leave the company though given he is probably got a while left to vest. As long as he isn't hindering your work and creating infighting/tension in a power struggle, it doesn't sound like he's a problem.
Honestly, it sounds more like you're jealous of his compensation relative to yours. Has your compensation been adjusted since you started working there? If you're now doing the work of a co-founder, you should be compensated as such. If your role truly has escalated, they shouldn't take issue with you asking to have an adjustment made to your compensation in recognition of that.